Brass Stacker Trapezoid Grip Slide Lock For Glock Pistols (Gsl) Slide Lock is shaped to allow for maximum finger purchase making field strip take down of your Glock a breeze The low profile design is approximately flush with the pistol frame reducing holster wear Brass Stacker manufactures theses from aircraft grade 4130 chrome-moly alloy steel and mill the barrel lug notch for superior "in battery" lock up Made in America with a 100% Lifetime Warranty Fits ALL generations including Gen 4's and the new G30S. Will not fit G36 or G42.